Disclosed herein is a method for depositing multicomponent films each of which may be stoichiometric or non-stoichiometric such as, but not limited to, Germanium Tellurium (GT), Antimony Germanium (SG), Germanium Antimony Tellurium (GST), Germanium Oxide, Germanium Nitride. Precursor compositions or mixtures thereof for depositing the multicomponent film using the method described herein are also contemplated.
Certain alloys such as but not limited to, GST (Germanium Antimony Tellurium alloy), and GeTe (Germanium Tellurium alloy) are used to fabricate electronic devices, including Phase Change Random Access Memory (PCRAM). Phase-change materials exist in a crystalline state or an amorphous state according to temperature. A phase-change material has a more ordered atomic arrangement and a lower electrical resistance in a crystalline state than in an amorphous state. A phase-change material can be reversibly transformed from the crystalline state to the amorphous state based on an operating temperature. Such characteristics, that is, reversible phase change and different resistances of different states, are applied to newly proposed electronic devices, a new type of nonvolatile memory devices, phase-change random access memory (PCRAM) devices. The electrical resistance of a PCRAM may vary based on a state (e.g., crystalline, amorphous, etc.) of a phase-change material included therein.
Among various types of phase-change materials used for memory devices, the most commonly used are ternary chalcogenides of Group 14 and Group 15 elements, such as Germanium Antimony Tellurium compounds of various compositions, including but not limited to Ge2Sb2Te5, and commonly abbreviated as GST. The solid phases of GST can rapidly change from crystalline state to amorphous state or vise versa upon heating and cooling cycles. The amorphous GST has relatively higher electrical resistance while the crystalline GST has relatively lower electrical resistance.
For the fabrication of phase change random access memory (PCRAM) with a design requirement less than 20 nanometers (nm), the demand for good precursors for GeSbTe atomic layer deposition (ALD) has been increasing since ALD is the most suitable deposition method for excellent step coverage, accurate thickness and film composition controls. The most widely investigated compositions of GST lie on the GeTe—Sb2Te3 pseudo-binary tie line. However, ALD deposition of these compositions is difficult because of the greater stability of Ge+4 precursors than Ge+2 precursors and Ge+4 tends to form GeTe2 instead of GeTe. Under these circumstances GeTe2—Sb2Te3 composition films would be formed. Therefore, there is a need for precursors and related manufacturing methods or processes for forming GT and GST films which can produce films with high conformality and chemical composition uniformity, particularly using an ALD deposition process.